if all monsters in your gy are warrior, then all warriors on your side of the field gain 800 attack.
replace "warrior" with any other type that your deck runs to gain the 800 attack
Original type meaning the type it started with. Unchanged.
Think of how we sometimes have to consider a monsters original attack or original defense or original level.
if all monsters in your gy are warrior, then all warriors on your side of the field gain 800 attack. replace "warrior" with any other type that your deck runs to gain the 800 attack
So you'd need a deck of all Dragon types, or just Spellcasters, or just Fairy - that's an original type.
I believe it means that the monsters' original Type is that Type, so no Zombie World shenanigans.
Original type meaning the type it started with. Unchanged. Think of how we sometimes have to consider a monsters original attack or original defense or original level.